THE PARTING PROCESS 


USED IN 



THE UNITED STATES MINT 

AT 

PHILADELPHIA. 



T. EGLESTON, Ph.D. 


From the School of Mines Quarterly, Vol. VII, No. 3, 

April, 1886. 





























Qr, US. B , 


THE PARTING PROCESS USED IN THE UNITED 
STATES MINT AT PHILADELPHIA. 



BY T. EGLESTON, Ph.D. 


The United States Mint at Philadelphia is a fire-proof building, 
containing besides the works ot the mint, properly speaking, 
large vaults for the storage of bullion and coin, and a museum 
of great historical interest. A parting process, invented in the 
year 1866, by Mr. A. Mason, the present superintendent of the 
New York Assay Office, but then its melter and refiner, is used 
for separating the precious metals. The same process is also used 
in the mint at San Francisco. It is carried out in both places very 
efficiently and cheaply. This process is known as the double 
process, as both nitric and sulphuric acid are used in it. It 
consists in inquartating the bullion, so that the gold shall consti¬ 
tute 100 parts in 285 of the granulated metal; this proportion 
leaves sufficient margin for any want of homogeneity that might 
occur in the granulated bullion, while the porous character of the 
resulting metal causes the acid to dissolve the silver more com¬ 
pletely, so that not more than 6 per cent, of silver is left in it- 
The residuum from the nitric acid is boiled twice with sulphuric 
acid, and makes gold 998 fine. This process is applicable to all 
kinds of alloys, and has been successfully worked since its inven¬ 
tion. It is much cheaper than the old nitric acid process, requiring 
very much less fuel and 20 per cent, less nitric acid. The sul¬ 
phuric acid part of the process is also very cheap, and requires 
but little apparatus and few men. 

A brief summary of the work of this mint during the year 
1884-1885 is given below. There were coined during the year 
$18,509,280.25 of gold and silver. This value was contained in 
42,864,328 different coins. The amount of gold coined during 
this time was 8,880,322 ounces, with a wastage of .002 of a standard 
ounce. The amount of silver treated in the same time was 
16,330,992.87 ounces, with a wastage of 2148.83 ounces, 1980.12 
ounces of which were stolen, so that the actual wastage of the year 


t&'S&ZK 



2 


was 168.71 ounces. The amount of gold and silver parted w; 
$3>38 1,962. The weight of the gold in gross ounces was 288,74; 
in standard ounces it was 153,390. Its value was $2,853,766. 
The weight of the silver in standard ounces was 453,919, and its 
value was $528,196. The charges collected from depositors for 
the parting were $12,188,02. The expenditures for doing it were 
$8250.97, leaving a profit of $3937.05. 

d he process used consists of eight operations. These are : 

1. Receiving and melting the deposits. 

2. Inquartation and granulation of the material containing gold. 

3. Solution of the granulations in nitric acid. 

4. Roiling the gold residues twice in sulphuric acid. 

5. Precipitation of the argentic nitrate with salt. 

6. Reduction of the argentic chloride with zinc. 

7. Sweetening and pressing the silver into cakes and drying the 
gold and silver. 

8. Casting the silver and gold into ingots and bricks. 

I. Receiving and Melting the Deposits. 

The United States Mint receives upon deposit, bullion in bricks 
and bars from all parts of the United States, and, besides, parts all 
articles of gold or silver, which it receives on deposit, to be assayed 
and their value ascertained. Large quantities of old jewelry, and 
of new jewelry out of fashion, of all kinds, watch-cases, and any 
other materials containing gold and silver, are received. Anything 
containing a sufficient amount of the precious metals is received 
on deposit, except that, so far as is possible, material containing 
tin is 1 ejected. This is the case with much of the cheap jewelry, 
which is filled with solder, and with watch-cases, which, within 
the past few years, have frequently been alloyed with tin, which 
is a difficult metal to separate with the appliances which are used 
at the mint. It might be melted with lead and cupelled, but 
there are no cupellation furnaces at the mint, and the refining by 
fluxes is very difficult, and gives a great deal of residue. Each 
deposit is melted by itself, and, if large enough, is cast in the 
slipper moulds, if not, into any kind of form. This deposit when 
melted, is numbered, assayed, and sent to the melting-room, where 
it is all mixed, so as to make the alloy of proper composition for 
parting, if it contains gold. 


ft r • . ' , % p 



•t 


3 

The deposit melting-room contains three furnaces of the same 
size as all the others in the mint. They use, however, charcoal 
as fuel. The gold is melted in Gunlack-Hessian crucibles, holding 
about 200 ounces each. The silver is melted in black-lead cruci¬ 
bles, Nos. 20 to 35, holding from iooo to 1200 ounces each. The 
whole work of this department is done by three men and one 
superintendent. They use about 100 bushels of charcoal per week. 

In melting the bullion a cover is almost always used. The cru¬ 
cible is so large that there is very little danger of the draft ever 
reaching the melted material. This cover is generally of charcoal 
or of bone ash. When the material contains metals which are to 
be oxidized, this cover is made of bone ash of an inch thick 
over the melted metal, and then nitre is added through holes made 
in it to oxidize the impurities. 

According to the quality of the bullion, this cover is renewed 
from time to time as is required. If it is very impure it may be 
renewed three times. Usually it is not done more than once or 
twice. When the metal is sufficiently purified the cover is care¬ 
fully removed and the metal fluxed with borax. The cover and 
the slag are ground, sifted, and washed to recover the small par¬ 
ticles of bullion. All the material from the bullion deposit room 
is toughened. If it is not sufficiently tough on the first melting, 
it is remelted with pulverized charcoal. 

Many of the silver bars which come from New Mexico and 
other localities, contain considerable amounts of arsenic and anti¬ 
mony. This metal is refined by putting into the melted bullion 
an iron bar four feet long, three inches wide, and from one-half to 
one inch in thickness, with which the metal is briskly stirred. 
A little nitre is added to the charge, and the metal is dipped with 
an iron ladle. This will generally remove all the antimony after 
two or three minutes of stirring. Before this method was devised 
it was found extremely difficult to separate the antimony from the 
bullion. When tin is present, pearlash is used, and thoroughly 
mixed with metal. If the slag is too thick a little borax is added. 
When iron and sulphur are present in either gold or silver, a flux 
of one part sand and two of nitre is used. Bone ash is used to 
thin the slag. When lead is present in either silver or gold, bone 
ash is used. Nitre is added, and holes made through the cover 
from time to time as it seems best. 

The fluxes which are generally used in melting are sand, borax, 


4 


sal ammoniac, soda, salt, and nitre. Sand is generally used when 
the gold or silver bullion contains iron. Borax is used when the 
metals are quite pure; sal ammoniac when the metal contains tin, 
or other substances difficult to separate. Nitre is used as a general 
oxidizing reagent, especially when the metal contains lead. When 
the slags are thick, soda is used to thin them, so as to make them 
deposit the granules of metal, and, if this is not sufficient, salt is 
added to it. Whenever any of these fluxes are used the metal is 
not allowed to come within six or seven inches of the top of the 
crucible. When the metal is entirely fused it is left for some little 
time in quiet fusion, and then stirred with a graphite stirrer held 
in the tongs, so as to give the whole force of the upper part of the 
body, in stirring to make the metal homogeneous, and not depend 
upon the wrists. Since this method has been introduced, very few 
melts have been found to be unequal in value at the top and the 
bottom of the ingot. As soon as it is stirred it is poured. When 
cast, the deposit is sent into the deposit-room to have its number 
marked upon it, and, subsequently, to be assayed to determine its 
value and fineness. 

They use in the deposit melting-room graphite crucibles, Nos. 
12, 20, 35, 50, and 70, made by Taylor, of Philadelphia. These 
usually last a week, or about 100 melts. Of the Hessian crucibles, 
which come five in a nest, only the two largest ones are used. 
They last for five or six melts. Anthracite coal is used for large 
melts and charcoal for small ones. 

When the deposits are received they are melted just as they 
come with fluxes and poured. If tough they are sent away at 
once. If not, they are melted under borax and charcoal until 
they are. Sometimes they require to be melted twice, and at 
others three times, until they are perfectly tough. 

II. Inouartation and Granulation of the Material contain¬ 
ing Gold. 

The melting-furnaces are on the first story directly under the 
parting-room. Here all the gold and silver is melted either for 
granulation or for ingots, which are the strips to be rolled out to 
make coin. The room is exactly the same size as the parting- 
house, and is divided into two parts by a chimney, which has four 
furnaces on each side of it, and three at one end, making eleven in 


5 


all, each of which takes a No. 70 graphite crucible. They melt 
35 o:) ounces of standard silver and 6700 ounces of standard gold. 
The silver bars weigh from 20 to 180 ounces, and the gold from 
100 to 200 ounces. The crucibles last 36 meltings of silver and 
24 of gold. Ingot melting is done every day of the week. 
Granulation is done only once a week, the metal being made 
of three parts of silver and one of gold. The granulation is 
done in water, which is cooled with ice. It is done in a cop¬ 
per vessel with a pan like that used in the New York Assay 
Office,* with three handles caught by three hooks. The back 
hook is very short so as to throw the pan forward to one side 
which has holes at the bottom in the rim on the front side, so that 
the water can drain off. When the granulation is finished the 
water is drawn off with a copper siphon, which connects with a 
pipe in the floor leading to the sewer, and fresh water added. To 
effect the granulation a wooden platform one foot high is placed 
in front of the furnace. The metal is dipped out of the crucible 
held high above the head, and poured in a thin stream with a 
slight wavy and rotary motion. The dore silver is not granu¬ 
lated, but is sent to the parting-house in ingots or bricks. 

III. Solution of the Granulations in Nitric Acid. 

The granulations are carried from the melting-room to the 
parting-room, which is on the floor above, in wooden boxes lined 
with copper, 18 by 13 inches and 6 inches deep, with two iron 
handles upon the outside for lifting them. The transportation is 
done on low platform wagons with iron wheels, which carry twelve 
or more boxes, and are raised to the level of the parting-house by a 
lift. The granulations are poured into a flaring copper pan 40 by 
33 inches on the top and 24 by 30 inches across the bottom, and 8 
inches deep. The rim is reinforced by a J^-inch half-round copper 
bar. It has two handles to carry it by, and, if necessary, to lift it 
when full. It is raised by a Weston pulley-block. The pan is set 
upon a table 25 inches high, which is directly against the wall 
next to a pair of platform scales, on the same level as the table. 
The granules are taken out of it with a copper scoop and put 
into a copper receiver on the platform of the scales and weighed, 
so as to get the exact quantity in each pot. The room in which 


* School of Mines Quarterly, vol. vii., p. 9. 




i 


6 

the parting is done is lighted on both sides and one end by large 
windows, but is not very light, owing to the proximity of other 
buildings. It is 80 feet long, 30 feet wide, and 12 feet 6 inches 
high, with a stone floor. The corroding-house is in the centre of 
one end. The pots are contained in a wooden house 23 feet long, 
10 feet high, and 5 feet 6 inches wide, the bottom of which is raised 
12 inches from the floor. The vertical sides of this house are 7 
feet high. The roof is inclined ; the peak of it is cut flat for a foot, 
and is two feet below the ceiling. The inside of this has a double 
lining .of boards, which can be taken out when it is too much 
eaten. The whole house is painted on the inside with asphalt, and 
on the outside with ordinary paint. On the bottom it is divided 
into two parts, each of which has two vats. The larger of these 
houses receives six parting-pots on a side, and the other five. 
Each section of the house has two tanks lined with 12-pound lead, 
on the side of which, three inches from the wall, is a special plank 
used as a splash-board, to prevent the throwing up of the water 
by the steam when it is boiled. Each of these tanks is 2 feet wide, 
and the length of half the house. Its depth is 22 inches. They 
are made of 2-inch plank. On the bottom of each of them a pipe 
is placed for the circulation of the steam to heat up the water. 

In each compartment of the house there are three doors on a 
side, which give access to two pots each, except the last door at 
the end of the smaller one, which gives access to only one. These 
doors are 40 inches wide and 45 inches high, and are made in 
wooden frames, the corners of which are reinforced by irons bent 
at right angles. They are counterpoised by weights hanging upon 
chains from each side, so as to allow the door to be opened to a 
height of 5 feet 9 inches above the ground, which is necessary to 
give the requisite space for handling the wooden stirrer used in the 
pots. Each one of these doors has two iron handles for the pur¬ 
pose of lifting it easily. The first house has all the doors alike; 
it is 12 feet 6 inches long. The other is 11 feet 6 inches long, and 
has two doors alike, and one of 28 inches, which gives access to 
only one pot. The whole house is braced with joists, which are 
4 by 3 inches between each door. They rise a few inches higher 
than the bottom of the doors when they are opened. 

All four of the tanks have water on the bottom to the depth of 
10 inches. This depth is regulated by an overflow pipe, so that 
it is always the same. These overflow pipes are in the centre of 


7 


* 


the side of the house, and the steam for boiling comes in at the 
two ends. 

The pots used are made of glazed earthenware. They come 
from Germany. Most of them are 21 inches in diameter and 22 
inches deep. They vary a little, however, the limits being 21 to 

24 inches in diameter and 21 to 22 inches in depth. Each of these 
has two conical handles on the outside, which are 6 inches wide 
and 5 inches high. Each has a spout 2 inches wide at the lip and 

inches deep. The weight of the corroding jars is 90 pounds. 
These are made in Germany, and do not crack by any heat that is 
produced by steam, and are only broken by accident. They were 
formerly made in this country, but caused so much loss by crack¬ 
ing, and were so easily broken, that only German ones are now 
used. They last for a long time, most of those on hand at the 
present time having been purchased during the war. They are 
set in the vats on a lattice-work of wood inches thick, to pro¬ 
tect the bottom of the tank from injury, with holes 4 inches square. 
This rack is set between the steam-pipes which run around the 
sides. These pipes are of copper, 1 ]/ 2 inches in diameter, and 
make the round of the tank next to the four sides of it. They are 
pierced on the insides with i^-inch holes every 2 inches. The pipes 
are thus behind the splash-board, the steam being discharged 
towards the interior of the tank. A wooden paddle, 33 inches 
long, with the flat 3 inches wide, 1 inch thick and 9 inches long, is 
used in each one of these pots to stir the mixture. The flue for 
the whole house is at one end. It is 29 inches on the bottom and 
1 foot high vertically. It then follows the slope of the roof so 
that at the highest point it is 2 feet. A flue from the chimney for 
cleaning the blanks for making the copper coins enters the 'side 
next the flue. From the brickwork the flue is continued in a terra¬ 
cotta pipe, finches in diameter, and set in a brick flue bound with 
iron. It descends vertically 30 feet, and enters a horizontal cov¬ 
ered culvert, 4 feet by 3, which is about 40 feet long, and connects 
with a chimney 8 feet 6 inches on the inside and 120 feet high. 
One hundred and twenty-five pounds of granulated bullion, a part 
of which, in some cases, consists of small silver coins which are 
condemned, are put into each one of these pots. 

The granulated bullion accumulated during one month will fill 
from 22 to 28 pots. Five pitchers of nitric acid, which each hold 

25 pounds of the acid at 40 B., are put into each pot, covering the 


8 


bottom nearly 9 inches. The whole height of the charge in the 
pot, including granulations, will be 12 inches, which about half 
fills it. Steam is introduced into the pipes on the bottom of the 
tank and the water brought up to a boil and kept so for twelve 
hours. In order to prevent them from getting clotted the granu¬ 
lations must be stirred every twenty minutes, each stirring taking 
about a minute for each pot. No cover is placed over the pots. 
They are left uncovered for greater ease of stirring. The sliding 
door for this purpose is raised, but the draft is so strong that none 
of the fumes come out into the room. The only acid fumes come 
from the transfer of the various acids. The workmen leave the 
building at six o’clock, but the steam is kept up until 8 p.m., at 
which time it is shut off. During these two hours the house is 
looked after by the night watchman. The water to thin down the 
argentic nitrate is not added until the following morning, when 
the bath is heated up for a few minutes to dissolve any crystals 
that may be formed. The water is added until it reaches to within 
3 inches of the top of the corroding pot. The solution is then 
drawn off with a gold siphon 1 x / 2 inches in diameter; this‘has a 
taper wooden plug 2^ by 1 3 ^ inches. The siphon costs $3600. 
The silver nitrate is collected in wooden tubs 18 inches in diameter 
and 15 inches high, made with staves 1% inches thick. They are 
held together by two hoops of 2-inch iron, and have handles on 
the inside for the purpose of carrying them. They last for two 
years. When the acid is drawn down to near the top of the gold 
th ree pitchers of fresh acid are added, and the granules are boiled 
for another twelve hours as before. Each charge thus remains in 
the pot forty-eight hours, during half of which it is constantly 
boiled. This last acid is not saturated. It is bailed into an adjoin¬ 
ing empty pot in the house, a leaden strip being placed between the 
two, so as to prevent any spilling into the water-bath. This acid 
is used on a fresh charge. 

The pitchers for the acid are of the same shape as the ordinary 
bedroom pitchers, but much larger. They are 18 inches high, 6 
inches in diameter in the opening above, and 9 inches at the belly. 
Besides the usual handle on one side, they have also one on the 
belly to lift them with. They are made of ordinary enamelled 
earthenware. They weigh 10 pounds each when empty. The 
nitric acid is brought to the lift in carboys. These are carried on 
wagons which hold two each, and turned at once into earthen pots 


9 


lS inches in diameter and 28 high. From here it is drawn into the 
pitchers. There are four of these receivers. Five pitcherfuls are 
counted to a carboy. When the acid is bailed down so that there 
is danger of taking out the gold, water is added to dilute the rest 
of the acid, and it is siphoned into a wooden tub on the floor 
outside the house. When the acid is dilute enough, the pot is 
lifted out of the house and the gold washed out of it into a filter. 
This filter is a round wooden tank, made of staves 1 inches 
thick; these are reinforced on the outside with others 2^ inches 
wide by 1 inch thick, leaving a space of \]/ 2 inches between each 
stave. The whole is bound with three hoops of 2-inch iron l /& of 
an inch thick, and is painted on the outside. The filter is 28 
inches in diameter on the inside at the top and 24 at the bottom. 
It has a false bottom, 4 inches above the permanent one, filled with 

inch holes, leaving 17 inches for the inner height of the filter. 
The false bottom is first covered with a layer of cotton cloth, which 
is brought up over the top and tacked to it. One thickness of 
Swedish filter-paper, which takes three sheets, is put over the 
bottom. Thick stiff brown paper is then put round the sides. 
Then a thickness of muslin, which, like the paper, is carefully 
pleated on the sides, is tacked over the top of the tub. The filter- 
paper is thus between two thicknesses of muslin. This filter has 
a wooden cover made in three parts. The whole filter is set inside 
of an iron frame resting upon a wagon, the frame is so arranged that 
the four arms by which it is caught shut over the wooden cover 
and make it quite tight, and form two eyes at the top by which it 
is lifted. Between the false and the real bottom there is a large 
wooden stopcock, with a i^-inch hole projecting 12 inches from 
the side, and supported by two irons hooked to the inside of the 
filter. Into this filter the gold in the bottom of each vat is poured, 
and the pots thoroughly washed to take out the last traces of gold. 
It is then raised to the overhead crane and carried to the large 
silver tank, where it is suspended, and the gold then carefully 
washed with hot water, which enters from an iron pipe in the ceil¬ 
ing, and is allowed to run by itself until it is perfectly sweet. This 
takes from two to three hours. 

The charge from 11 pots will be about one^ foot high on the 
bottom of the filter. When the gold is quite sweet the tank is 
lowered to the ground and the gold is removed from the cloth by 
earthenware dippers to be treated by sulphuric acid. The upper 


2 


IO 




muslin of the filter lasts for two operations, the lower one lasts for 
three. When they are no longer strong enough to bear the weight 
of the gold they are dried and burned, and the gold recovered 
added to the other gold. 

IV. Boiling the Gold Residues Twice in Sulphuric Acid. 

The gold from the filter is carried to 4 furnaces, which are hex¬ 
agonal in shape, 25 inches high by 28 inches across. These are 
made of boiler iron with cast-iron doors and tops, and are lined 
with brick. Anthracite coal is used in them exclusively. The 
cast-iron cover is inches thick. The top has on the outside a 
rim J^-inch deep. In its centre is a hole 21 inches in diameter 
with an inclined flange 2 inches wide, having the same angle as 
the bottom of the sides of the pot in which the gold is to be treated. 
This rim rises half an inch above the top, so that there is a basin 
half an inch deep all around the top of the furnace to catch any¬ 
thing that may be spilled over the sides of the cast-iron pots. 
This hole has a cover \ ]/ 2 inches thick. In the top of this furnace 
a cast-iron pot, with three legs 3 inches long, is placed. It is 
nearly hemispherical, being 22 inches in diameter at the top and 
12 inches deep in the centre. It has two trunnions. When set in 
the hole of the furnace 7^ inches of the pot are above it. The 
trunnions prevent its passing in any further. It is intended that 
the bottom of the pot should fit the flange pretty nearly tight. 
With these trunnions, when the operation is finished, the pot is 
lifted by two men, by placing a piece of gas-pipe over the trunnions, 
so as to give a handle long enough to get an easy purchase. The 
lid of the furnace is then slid under for the pot to rest on. It was 
originally intended to lift these pots by the trunnions with a Wes¬ 
ton pulley-block and carry them away on an overhead railway, but 
it has been found easier to lift and carry them by these pipe handles. 
The pots are closely covered by a conical lead hood, with a pipe 
6 inches in diameter made of 12-pound lead sliding in another 8 
inches in diameter. The hood has a hole in the side 7 by 6 inches, 
which is covered with a piece of sheet lead bent over at the top, 
so that it can be easily removed when its contents are to be stirred. 
These hoods are counterpoised with weights so as to be easily 
lifted. Eight feet above the furnace is a reservoir 2 feet square, the 
length of the four furnaces, and lined with 12-pound lead. It is 


inclined to one corner. The 8-inch pipe enters the bottom and 
rises two inches above it. In the centre of the box is a flue lead¬ 
ing to the terra-cotta pipe in the ventilating flue of the parting 
house. Whatever acid condenses in the box flows to the corner 
and is carried by a lead pipe to a vessel 7 inches in diameter and 
12 inches high on the floor. The rest of the acid escapes into 
the flue. 

The gold is dipped out of the corroding pots with a porce¬ 
lain vessel 6 inches in diameter and 4 inches deep with a porcelain 
handle 5 inches long. Under this a porcelain vessel 10 inches in 
diameter and two inches deep is held to catch any gold that might 
possibly fall. Ten of the porcelain scoopfuls are put into each 
one of the iron pots. One pitcherful of sulphuric acid at 66 B. is 
then added in each pot. This acid weighs 32 pounds. It is boiled 
for 1 y 2 hours. By this time it has nearly evaporated. A second 
pitcherful is put on and boiled for the same time. The pot must 
be stirred every ten or fifteen minutes, which is done through the 
opening in front, with an iron rod the end of which is hammered 
out into a four-pronged rake, the prongs being 3 inches, and the 
whole rake 3 feet, long. This is done to prevent the gold from 
agglomerating on the bottom. By this time the gold is 996 to 
998 fine. If wanted finer than this it is boiled a third time, and 
can easily be made 999^ fine. The excess of acid is poured off 
to be used again. The acid from the gold is put into a lead-lined 
vat 20 inches in diameter and 24 deep, lined with 8-pound lead, 
bound with three iron hoops and diluted with water, and the silver 
contained precipitated in the porcelain pot. The residue of sul¬ 
phate of lead and silver is allowed to collect. The gold after being 
carefully washed with water is kept in a porcelain solution-pot 
under water. All the wash-water from the gold is treated in the 
same pot. When small samples are treated the gold residues are 
filtered on a frame two feet square the inside of which is 20 inches 
square, a single thickness of muslin is tacked to this and over the 
muslin two thicknesses of filter paper are placed. The gold is 
washed down the sides of the filter paper with a two-quart pitcher. 
The liquor is saved and added to the silver liquors. When sufficient 
gold has been collected it is carried to the drying furnace in the 
cellar, which is similar to the drying furnace for silver, but a little 
smaller. It is not pressed into cakes, but when dry is sent directly 
to the melting-room. 


12 


The sulphuric acid is stored in a vat made of 2 x / 2 inch wood, 
23 by 19 by 20 inches deep. This is covered inside and out with 
12-pound lead and holds 2]/ 2 carboys, which do not fill it quite to 
the top. The acid is dipped out of this with a two-quart pitcher. 
The large pitchers are set upon a lead plate 2 inches larger in 
diameter than the bottom of the pitcher to make sure of catching 
any acid that may drop from the outside. The tank and the pitch¬ 
ers are set upon a platform six feet long and an inch wider than 
the carboy, with a rim 2 inches deep, lined inside and out with 12- 
pound lead. The tank is set at one end, and the pitchers at the 
other. Each pitcher is set upon a lead basin so arranged as to 
allow the pitchers to drain perfectly from any acid that may be 
spilled on the outside. 

V. Precipitation of the Argentic Nitrate with Salt. 

All the nitrate solutions from the eleven pots go to a large tank 
to have the silver precipitated. This tank is ten feet by eight, and 
four and a half deep. It is made of three-inch staves which are 
reinforced on the outside by others 3 inches wide by I inch thick, 
with the space of 3 inches between each stave. This is held by 6 
hoops 2inches in width of ^-inch iron. The tank is set 3 feet 
above the floor. It is 4 feet deep on the inside, and 4 feet 6 inches 
deep on the outside. The salt solution for precipitating the silver 
is made in a tank on the floor above, the water being allowed to 
take up as much salt as it will dissolve. The salt for this solution 
is brought up in bags which contain one bushel each. The solu¬ 
tion is conveyed to the tub in iron pipes and is run into the tank 
until it is one foot deep on the bottom. The whole is stirred by a 
wooden dasher 2 feet wide by 1 foot high with a handle 3 feet 
longer than the longest diameter of the tub. It takes two hours 
to bring the solution from the corroding jars and thoroughly pre¬ 
cipitate the silver from it. After 6 pots have been added the liquor 
is thoroughly stirred. A platform is placed on the outside across 
one of the longer diameters of the tank which is 6 feet high and 7 
feet long, 18 inches wide in the centre and 34 at the sides, being 
cut out to fit the shape of the tub. The top of the platform is 
reached by 6 steps on wheels, 6 feet wide, which are rolled out of 
the way when the silver chloride is carried to the reducing tank. 
On the opposite side is a platform 28 inches by 32, hung to the 


13 


sides by iron bars which can be moved to any part of the tank 
when required. It is 58 inches above the ground. A ladder is 
also used to reach any part of the tank when it is necessary. 
When the test shows that the silver is all out of the liquor it is 
again thoroughly stirred with a dasher and the heavy parts of 
the precipitate pushed to the side of the tank where the spout is 
on the long diameter of the tank. The whole of the liquor will 
be about 14 inches deep on the bottom of the tank. The spout 
by which it is emptied is 18 inches long, 4 inches in diameter, 
with a discharge hole 2^ inches in diameter. It is supported 
by two iron rods attached to the side of the tank. This spout 
projects over a tank on a wagon the top of which is 2 feet above 
the bottom of the floor. This tank is 6 feet 6 inches long, by 
2 feet 7 inches wide and 15 inches deep. It is lined with 12- 
pound lead. It is set upon a frame" on the top of the wagon, 
which is 3 inches thick and 9 inches high. This top inclines to the 
centre and also to one end leaving a space of 3 inches at the lower 
end between the top and bottom of the tank. The bottom of the 
tank is filled with holes J^-inch in diameter, and over these and 
the sides of the tank twilled cloth is put and kept to its place on 
the sides with a frame made of half-inch stuff painted. Both the 
frame of the filter and the wagon top have their corners reinforced 
with iron. The silver chloride tank is independent. It rests upon 
a cleat on the large frame, which is securely fastened about 2 inches 
from the bottom of the frame. The top of the truck inclines 
toward the centre and one end. Under the centre of this end 
troughs made out of a single stick 7 inches wide and 434 inches 
thick hollowed out in the middle are placed. The one next the 
tank projects a few inches under the bottom of the tank. The 
thickest of the silver chloride on the bottom of the precipitation 
tank is pushed by the dasher to the stop-cock and made to flow 
on to the filter till it forms a bed 2 or 3 inches in thickness. This 
is called a bottom. After this has been done the rest of the con¬ 
tents of the tank is made to flow over this bed,- which is thick 
enough to prevent any fine silver chloride from passing through 
the cloth. While the silver chloride bottom is being formed the 
liquor does not run through the filter clear, and low wooden pails, 
13 inches in diameter and 8 inches high with copper hoops and 
handles, are set under the trough to catch it. As long as it is 
turbid this liquor is thrown back into the vat. When a glass full 


l 4 


held against the light is perfectly clear, the pails are removed and 
a trough like the others, but 6 feet long, is placed under the 
bottom trough and carries the excess of liquor away. The silver 
chloride is washed for about four hours. It is tested both by 
color and by paper to see when it is perfectly sweet. 1 he silver 
chloride is washed with cold water until sweet. This water runs 
through two or three traps and then goes to the sewer. 

/ 

VI. Reduction of the Argentic Chloride with Zinc. 

The wagon, with the silver chloride in the tank upon it, when it has 
been completely drained is moved to a tank between the precipitation 
tank and the gold-refining furnaces. This tank is 6 feet long by 3 
feet 9 inches wide and 18 inches deep. It is lined with i^-incli lead. 
This lead lining lasts for two or three years and then gives out in 
the seams. The corners of the bottom of this tank are rounded 
for greater ease in stirring. Four boxes 20 by 12 inches and 6 
inches deep made of ^-inch wood with two iron handles on the 
outside, filled with granulated zinc, are thrown into the tank to 
reduce the silver chloride. These will generally be sufficient, but 
occasionally 4^2 boxes will be required. The calculation is gen¬ 
erally made that it will take 2 boxes for 11 solution pots, but it 
sometimes takes a little more. The zinc box weighs, when empty, 
10 pounds, and when full of zinc 42 pounds, so that each box 
contains a charge of 32 pounds of zinc. 

The silver chloride is shovelled out of the vat on wheels with a 
copper scoop shovel. The chloride is put into the tank first, and the 
zinc stirred through it afterwards. The action of reduction should 
commence at once; but if it does not, a pint of sulphuric acid is 
added to make it begin. It is stirred with a wooden stirrer, 4 feet 
4 inches long, with the shovel part 10 by 17 inches, and 2 \ inches 
thick, the end of which is cut down to a sharp edge. One man 
must stir it very actively for an hour. After this it need only 
be stirred occasionally. It takes four hours to finish the whole. 
When the reduced silver is very dry a little water is added to dis¬ 
solve out the zinc sulphate. 

This vat was formerly covered with a lead-lined hood counter¬ 
poised, and having a chimney, 14 inches square, going to the roof. 
This was raised from time to time as needed in the working. It 


15 


was very heavy, and the men eventually became afraid of it, so it 
was taken down. They say they do not feel any great inconve¬ 
nience from the gases evolved. The charge in the tank is 12 inches 
deep on the bottom. When there is no further action, three pitchers 
of sulphuric acid, weighing 32 pounds each, are added to dissolve 
out any excess of zinc. The vat is allowed to lie all night with the 
acid in it. The reduced silver is pushed to one side, and any liquor 
in excess is drawn off with a copper siphon. 

The zinc is granulated in a copper tank like the bullion granu¬ 
lating tank. It is 32 inches in diameter at the top, and 27 inches 
deep, and slightly flaring. It has two handles on the side. A pan, 
26 inches in diameter and 6 inches deep, fits into this. It has three 
handles, two at the ends of one diameter, and one at the diameter 
at right angles to it, and is in all respects like the silver granulating 
tank. The zinc is melted in a crucible in a furnace exactly like 
the melting-furnaces, and is poured into this tank with a rotary 
motion. A ^ inch pipe discharges cold water into the tub ; a 1 
inch iron pipe, 15 feet long, carries the escaping water to the sewer. 
When the pan is full it is raised by a pulley. The handles cause it to 
tip to one side. It is suspended over the top of the tank to drain, 
the front of the pan being perforated so that the water flows back 
into the vat. The zinc from the pan is thrown into a wooden, 
hopper-shaped reservoir on wheels. This is 35 by 30 inches on 
the top, and 40 inches high. On the bottom there is an opening 
one foot high the whole width of the box. In front the bottom 
extends into a shelf 16 inches wide. The granulated zinc is re¬ 
moved from here with a shovel. One of these cars full lasts for 
four reductions. 

VII. Sweetening and Pressing the Reduced Silver into 

Cakes. 

The reduced silver is taken out with a copper scoop 10 inches in 
diameter and 5 inches deep, with a shovel-handle, and put into a 
colander. This is a cylindrical, wooden vessel on wheels, lined 
with 8-lb. lead, which is turned over at the top. It is 3 feet in 
diameter, 20 inches deep to the false bottom, which is 6 inches 
above the other. It has four i^-inch iron hoops. There is a 
one-inch overflow pipe at the top and running down the sides. 
The silver here is washed with hot water until it is entirely sweet. 


i6 


Before putting in silver the lead bottom, which is filled with 
quarter-inch holes, is covered with one thickness of twilled cloth, 
and is filled to within four inches of the top. The water runs out 
as fast as it runs in. This water flows into a box with two parti¬ 
tions, and from there to a box with four partitions, and from there 
to the sewer. These boxes are simply used as a precaution. Not 
more than -two or three ounces of silver per year is caught. 

The nitre used in the melting was formerly made in the mint 
from the nitric acid used to brighten nickel coins. This was satu¬ 
rated with soda under a wooden hood, and concentrated at a very 
low heat in an iron vessel lined with lead, and crystallized for use 
in the melting department. 

The articles contained in the parting-house are : 

22 German corroding jars. 

6 American “ 

7 pitchers for nitric acid. 

2 earthen reservoirs for nitric acid. 

1 lead tank for sulphuric acid. 

2 two-quart pitchers for “ 

7 wooden stirrers. 

i porcelain jar for the wooden stirrers. 

1 wooden tub for copper scoop and shovel. 

2 silver nitrate tubs. 

2 salt trucks. 

7 silver chloride dripping-tubs. 

2 sulphuric tubs for cleaning gold. 

2 large tub filters for gold. 

I “ “ “ silver. 

1 silver chloride tank. 

2 “ reduction tanks. 

2 zinc vats on wheels. 

4 boxes to measure charge of zinc. 

6 carboy trucks for square boxes. 

i iron truck for round carboys. 

i copper scoop. 

i copper shovel. 

1 porcelain scoop and basin. 

4 iron stirring rakes for gold. 

2 iron scrapers to clean up the floor. 


Every time a colander is filled and washed, it is carried to the 
hydraulic press in the cellar. The silver is put into a circular 
mould 12 inches in diameter and 12 inches deep. The plunger 
of the hydraulic machine fits this mould rather loosely. The 
silver is patted down with a round wooden stamper 4 inches in 
diameter and 4 inches high, with a handle 5 inches long. The 
plunger is then made to descend until the cake is only 4 inches in 
thickness. About a gallon of water is forced out of each cake, 
which is caught on the filter. The silver is dried in the same kind 
of a furnace as the gold, but still contains water, so that it shrinks 
considerably in drying. The shrinkage amounts to nearly two 
inches in the diameter. The water from the hydraulic press formerly 
ran through six traps, but it is now caught on a twilled muslin 
filter; the water runs from that directly to the sewer. 

In November, 1885, ten colanders were sent to the press. With 
six men three runs of eleven pots are the most ever done in a week. 
The business of the mint is much less than it formerly was, for in 
1848-9, during the gold excitement in California, 56 pots were 
done in a week. 

The gold-drying furnace is 3 feet by 6, and 4 inches deep. It is 
made of y% boiler iron, and is covered by a rectangular hood. From 
the top of this hood, in the middle, a pipe, 12 inches square, con¬ 
ducts the steam to the chimney which carries off the smoke. 
The front of the hood inclines a little, so that the top is slightly 
smaller than the bottom. It is 22 inches high. It is hinged so 
that it can be raised to give access to the whole of one side of the 
furnace. In the centre of this door there is a small one 11 inches 
square, which is used for observation during the process. An iron 
shovel and a copper scoop are used both to introduce and to remove 
the gold. It contains very little dust, as the gold from the sulphuric 
acid is generally coarse, and there is no fear of dust in melting, as 
the hood over the melting-pot stops the draft. 

The silver-drying furnace is 7 feet by 38 inches, and 4 inches 
deep, the pan being made in the same way as the gold pan. It 
holds 20 cakes. The flue of the fireplace in both of these furnaces 
passes through the centre of each, and directly under the pan. 
The ash-pit is 2 feet deep. The wood used is pine, three feet 
long. There are no grates to the fireplace, but the end of the 
wood rests upon iron in front, and the brickwork at the back, 
which is protected from abrasion by an iron plate. The gold 



i8 


and the silver are brought in deep copper trays, set upon wagons. 
The trays for the gold are 39 inches by 20, and 16 inches deep. 
For the silver they are 36 x 24, and 18 inches deep. The silver 
cakes are piled up in the bottom, two in a row. There will 
thus be three rows, of six each, piled one on top of the other, 
and in the centre at the top two, care being taken, as far as pos¬ 
sible, that they should not touch the copper sides. The cakes, 
as they come from the furnace, are shrunk unequally ; those in 
the centre, directly over the flue, are the most contracted. They 
are often brought up to a red heat, and sometimes contract as 
much as two inches in the diameter. Those upon the sides fre¬ 
quently do not contract at all, or are very much less contracted 
than those in the centre. 

The furnace is fired while some other work is being done. It 
requires very little attention. The fireplace is 14 inches square, 
the wood being lighted with shavings put into the ash-pit and 
allowed to burn out, and another charge of wood put in. It usually 
takes three firings, with the furnace full of wood, to heat the silver, 
and I y 2 for the gold. 

VIII. Casting the Silver and Gold into Ingots and Bricks. 

In the ingot melting-room the furnaces are arranged two upon 
one side against the central flue, with their coal-bins. One of the 
furnaces is used for granulation. There are, beside these, two 
others at the side of the room. In the next room therd are three 
against the chimney and four at the end of the room on the main 
wall, making eleven in all. The crucibles used are of graphite. 
They are set in the furnace on half fire-bricks made for the pur¬ 
pose. When the ingots or bricks are too long for the pots graphite 
rings, 3 inches deep, are put over the top of the crucible with a 
cement of borax and silica. This melts and fastens the ring 
securely to the pot, making it perfectly tight. When the melt is 
finished, just before the last dip is taken from the crucible, this rim 
is pried up with a poker, and is easily removed. The pot is then 
used as before. These rings can be used three days. 

When a pot is to be charged all the material is brought in a 
copper-lined box 18 by 13 and 6 inches deep. The part of the 
melt in small pieces is taken up first in a copper scoop. The 
larger pieces are then lifted upon the scoop by the hand. An iron 


19 


hood, with two handles to lift it, is then placed over the pot, the 
round part of the bottom of which is the size of the outside of the 
top of the pot. The front fits over the incline of the front of the 
furnace, so as to effectually shield the men from the fire and pre¬ 
vent any danger of dropping a part of the charge into the fire. 
Usually there will be a little metal in the bottom of the pot from 
the previous melt, which cannot all be dipped out. The small 
pieces are added very carefully at first, and the larger ones as care¬ 
fully on top of them to prevent any splashing. When the metal 
is in brick form, too large to go to the bottom of the pot, the cover 
is put over the brick on the door side, inclined so as to protect it 
as far as possible from the air. The fire is kept up as actively as 
possible. In order to prevent the air from coming in by the sides 
of the door, bars of iron are placed against it. 

The time of melting is usually for silver one hour and ten 
minutes, for gold one hour and forty-five minutes, per melt. 
Anthracite coal is used exclusively in this department. When 
the metal is quite melted it is thoroughly stirred just before cast¬ 
ing. For silver this is done with a round iron disk, 6 inches in 
diameter and ^ inch thick, pierced with eleven rows of j^-inch 
holes. This is set in a stirrup of ]/ 2 -inch iron, the attachment 
being made to the side of the disk only. This stirrup is 9 inches 
long, and it is attached to the rod. The whole length inside the 
handle is 37 inches. The handle is bent round, and is 3 by 5 
inches. It is moved up and down in the melted silver from the 
top to the bottom of the crucible. After some use this disk 
becomes bent, and the iron is eaten into, by the metal, in a very 
irregular manner, but always in the direction in which the iron 
has been rolled. These stirrers last, when in constant use, ten days. 
For gold, the stirrer is made of black lead. It is 17 inches long, 
I inches wide, and 1 inch thick on the upper part. The lower 
part gradually widens until, at the bottom, it is 3 inches wide. 
At this point there are three holes, two below and one above, 
inch in diameter, which go through the stirrer. The upper 
part is straight, but the lower part is slightly curved like a table- 
fork. The graphite stirrers for gold last three to four days. They 
are usually broken by accident, and do not wear out. They are 
held in a pair of pincers. The men step up on the wooden plat¬ 
form in front of the furnace and seize the tongs with both hands, 
stirring the metal in the pot with a movement from the shoulder, 


20 


in this way stirring the metal most effectually with the least labor. 
The cups for dipping the gold and silver are also held in tongs 
when in use. They are made of graphite, expressly for this pur¬ 
pose, and last two or three days. They do not wear out, but are 
usually broken by accident. The pot covers last three or four 
days. 

Connected with each fusion furnace are the following articles : 

I iron scoop for charcoal. 

i iron coal-bin and shovel. 

i iron scoop to hold the metal. 

i iron scoop, io by 6 inches and 3 inches deep, with handle 6 
inches long, for collecting the scum taken from the pots. 

1 iron shoe-mould to cast the metal in case of accident. 

1 pan for granulated silver, 18 by 12 by 6 inches. 

1 hood for charging the crucibles. 

1 flat poker, 3 feet long by 1 inch wide and inch thick, turned 
up 1 inch at the end. 

1 pair tongs to remove the grate bars. 

1 spring tongs. 

1 differential pulley for two furnaces. 

1 duster. 

Each furnace-man has a pair of crash mittens, made very heavy, 
and stuffed with old carpet, so as to be able to handle everything 
hot. 

Two assays are made from each pot: the first after the first ingot 
has been poured, when some of the metal is granulated in a cup. 
The granulating cups are made of copper, and hold about a pint 
of water; twenty-four of them are set in a rack in two rows of 
two, and are filled with cold water. The hind one is marked with 
chalk No. 1, and the front one No. 2. The samples are marked 
to correspond. The number of the melt is also chalked upon the 
cup. The first melt is marked No. 1. The second is taken out 
just before the last ingot is poured, and is marked No. 2. If the 
assay shows that the metal is of a proper fineness, the ingots are 
sent to the coining department; if not, they are remelted. When 
the assay sample has been taken by chipping, the chips are put 
into a copper pan, which is marked in the same way. 

Assay samples for standard silver are alone done by granulation. 


21 


The assay samples for gold and fine silver are taken by chipping 
from the down corner. No dore metal ingots are made at the 
mint. 

In thirteen hours six tons of standard silver ingots are cast, 
which keeps six furnaces occupied. The others are used either on 
gold or on granulations. The work is somewhat intermittent, but 
is quite severe while it lasts. 

Including all the men of the deposit-room and parting-house, 
there are thirty-eight men employed in this department. In the 
melting department alone thirty-two men are constantly engaged. 
These men are occupied as follows : 

8 opening and closing moulds. 

7 melters. 

4 fillers. 

3 men in the parting-house. 

3 men in the deposit melting-house. 

3 grinding cinders, etc., in the cellar. 

2 tapping ingots. 

2 picking up and pickling ingots. 

i foreman in the deposit melting-room. 

i foreman in the coin melting-room. 

i overseer. 

I collier. 

i gatekeeper. 

I man at the hoist. 

The loss in weight in the treatment is estimated at one-tenth 
ounce for every thousand ounces. The melting of standard silver 
is done under granulated charcoal, entirely free from dust, made 
for the purpose. On fine gold and silver the charcoal cover is 
only used to prevent the action of the air. Fine gold, which is 
base, is first mixed with fluxes, and charged in the pot when the 
hood is on it, and is melted very slowly. The fluxes used for 
separating the different materials from gold are as follows: When 
arsenic is present the gold is melted under a bone-ash cover, and 
a hole about 2 inches in diameter is made in the centre, nitre 
being poured in around the circumference after the metal is in 
quiet fusion. When this is saturated it is removed. It generally 
takes two or three hours to remove the arsenic, but it can be done 


I 


22 

in this way. When lead is present the same is done, but it takes 
less nitre, as the bone-ash absorbs most of the lead. When anti¬ 
mony is present the metal is liquated and the antimony separated 
in the same way as the arsenic, but every cup taken from the melt 
must be tested. It is best removed by cupellation with wood as a 
fuel, the flame striking the metal. When tin is present bone-ash 
and nitre are used. All the dampers in the flues are closed while 
working with the stirrer. The quantity of nitre added has to be 
very large. 

For the impurities in silver, when antimony is present, the metal 
in fusion is stirred with a large piece of iron for about five minutes. 
When arsenic is present bone-ash and a little nitre are used. The 
cover is allowed to stand until the bone-ash flakes, when it is removed 
and fresh bone-ash added until there is no flaking. For lead bone- 
ash is used alone. When tin is present in silver, if there is any 
gold, it concentrates in the gold, and is separated in the same way. 

The whole floor of the melting-room is covered with an iron 
grating full of hexagonal holes. The grating is in hexagonal 
pieces, 12 inches across. They cost 8 cents a pound. This grating 
pays for itself every three months, when it is taken up and the 
floor swept, and the silver and gold which would otherwise be lost, 
recovered. Beside the coin that is made for circulation, silver bars 
999^2 fine, which vary from 20 to 180 ounces in weight, and gold 
bars, from 5 to 243 ounces in weight, with a fineness of 999, are made. 
These are stamped with their fineness, weight, and value, and pass 
current just as the larger bars and bricks made in New York. 

The ingot moulds are made of cast iron, in three pieces, planed 
up so as to have two ingot moulds in the same piece. They are 
clamped together with a strong iron screw, so that they can be 
easily separated. All three of the parts are greased with lard, put 
on with a swab, before they are used. The lard is purchased, by 
contract, free from water. The kegs are stored in the basement of 
the building, and what is used is held in a copper box 12 inches 
by 6 and 4 inches deep, with two handles at each end. At one of 
the ends there is a space 4 inches long, and the depth of the box, 
to hold the grease. The other end is raised to within 2 inches of 
the top, and this grease, taken from the deep part of the box, is 
spread over the surface, and the grease taken up by the swab from 
here and spread over the mould. This is done so as not to get 
too much grease on the swab. Standing at right angles to each 


23 


v 


furnace is a table made of wood, whose top is 2 feet by 18 inches. 
It is 18 inches high, with two projecting handles at each end at 
the top for the convenience of carrying the table when it is neces¬ 
sary to move it. On the top of this is a cast-iron pan to receive 
the ingot moulds, which are set on the bottom in two rows. These 
pans are 4 by 2 feet on the top, and 3 feet by 14 inches on the 
bottom, and 6 inches deep. Their object is to catch any silver or 
gold that may be dropped from the cup during the casting. The 
sides flare to an angle of about 45 °. This table, like all'the other 
heavy tables, is set upon full hexagons of iron, the same size and 
thickness as the grating, so that when the floor is to be cleaned, these 
heavy tables need not be moved. The hexagons are 1 foot from side 
to side. Eighteen double-ingot moulds are placed upon the table at 
one time. As soon as the mould is filled, it is removed by a man, 
wearing very heavy gloves, to a table in front. This table is 8 feet 
long, 2 feet wide, and 30 inches high. The top is made of wood 
4 inches thick, covered with a plate of cast iron 2 inches thick, 
with four rims running the full length of the table, ^ of an inch 
wide and 1 inch high, the object of which is to keep the hot 
moulds and the ingots off of the body of the cast iron, and thus 
prevent its becoming heated. One man brings the moulds and 
opens them on the same side of the table as the furnace. On the 
opposite side a man with a copper tongs seizes the two ingots from 
each mould and places them on the end of the table until three 
moulds are open. He then seizes the six ingots in the copper 
tongs and plunges them into a rack in a bath of weak acid. This 
is contained in a box 22 inches square and 16 inches deep, made 
of 2-inch wood, and lined with 18-pound lead. On the bottom of 
this box upright copper bars, set in a rectangular frame, are placed. 
This box is covered with a hood. A quart of commercial sulphuric 
acid is put into it. The hot ingots cool off in this pickle, the six 
together. When cool, they are removed by the same man and 
put into a box, 24 inches by 18 inches and 10 inches high, made 
of sheet copper, into which cold water runs in and out to wash off 
the sulphuric acid. The top of this box is 24 inches above the 
floor, and on the same level as the pickle box, and at a convenient 
distance below the table. It has the same kind of a rack as the 
pickle box into which the ingots are set. The small amount of 
silver in the pickle acid is precipitated, washed, and taken to the 
parting-house. After the ingots have remained in the water for a 


24 


tew minutes they are removed and put into a wooden box in front 
of the copper tank, and from there are collected to be prepared 
for the rolls. There are two of these cooling and pickling vats in 
the same room. As soon as removed these ingots are taken to a 
bench, where there are two men with iron vices, protected with 
copper plates over the jaws. The jaws are opened by a treadle 
commanded by the foot. The edges of the ingots are filed off 
roughly. There are four of these benches, with two men at each 
bench, two benches being in each division of the large room. As 
soon as filed they are collected, and go to a shear press to have 
the upper end of the ingots cut off, leaving the lower one wedge- 
shaped as it came from the mould, to facilitate its entrance into 
the rolls. They are then weighed, and if the assay shows the 
metal of proper quality they are sent at once to the minting de¬ 
partment. 

The ingot moulds are made of various sizes for the different 
denominations of coin to be made. They are all double except 
the quarter eagle, which has four divisions. All these moulds are 
13 inches in length, and are wedge-shaped at one end. Their 
width only is variable. For the $20-gold piece they are 1 y 2 inches 
wide and ]/ 2 an inch thick; for the $io-gold piece they are \ y& 
inches wide ; for the $5, j jj of an inch ; for the $3, T 7 6 of an inch ; 
for the $2.50 f-Q of an inch, and four to a mould; for the $1, 1^ 
inches. For the silver, the $\ is ifo inches wide; the 50 cents, 
1^6 inches; the 25 cents, 1 y% inches; for the 10 cents the dollar 
ingot is used, two rows being cut out of it. 

The melting and pouring of the silver dollars takes hours, 
of the 50-cent pieces 1^ hours, of the 25-cent pieces 2 hours. 
In these melts there are 74 dollar ingots, 85 fifty cent, 126 twenty- 
five cent, for the silver. For the gold the ^20-pieces have 60 
ingots to a melt, and take 1 ]/^ hours; the $io-pieces have 96 to a 
melt, and take 1 *4 hours; the $5 and the ^3-pieces 150 to a melt, 
and take i 2 / z hours; the $2. 50-pieces 250 to a melt, and take 2 
hours; the $1 -pieces 96 to a melt, and take 1 ]/ 2 hours. 

The different denominations of coin have each its own special 
benches. Each of these benches has eighteen moulds. For the 
silver coins, there are six benches for the dollar ingots, three for 
the half-dollar, three for the quarter-dollar, and for the ten-cent 
the same as the dollar. All the ten-cent pieces are made at the 
dollar tables. For gold, there are two for double eagles, two for 


25 


eagles, two for half-eagles, eighteen for quarter-eagles, ten forthree- 
dollar pieces, and thirteen for one-dollar pieces. 

List of articles used in the melting-room : 

36 wooden boxes lined with copper for alloy. 

6 trucks for carrying alloy, etc. 

36 alloy boxes, 17 by n by 4 ^ inches, for the silver melts. 

72 ingot boxes 18 by 12 by 6 inches. 

60 granulating boxes 20 by 15 by 5 inches. 

2 boxes for silver toppings. 

1 box for gold toppings. 

300 No. 70 graphite crucibles for silver and gold. 

250 dipping cups. 

250 No. 70 rings. 

250 No. 70 pot covers. 


The following table gives the legal weight and fineness of the 
coins of the United States, and their diameter and thickness: 



Legal weight 
(grains). 

Fineness 

(thousandths). 

Diameter 
(2oths of an 
inch). 

Thickness 
(ioooths of an 
inch). 

Gold: 





Double eagle. 

516 

900 

27 

77 

Eagle. 

258 

900 

21 

60 

Half eagle. 

I29 

900 

17 

46 

Three dollars. 

77-4 

900 

l6 

34 

Quarter eagle. 

64-5 

900 

15 

34 

Dollar (new). 

25.8 

900 

I I 

r8 

Silver: 





Trade dollar. 

420 

900 

30 

82 

Standard dollar. 

412.5 

900 

30 

80 

Half dollar. 

192.9 

900 

24 

57 

Quarter dollar. 

9645 

900 

19 

45 

Twenty cents. 

77.16 

900 

I lYz 

47 

Dime. 

38.58 

900 

14 

32 

Half dime. 

19.2 

900 

12 

23 

Three cents. 

11.52 

900 

I I 

18 

Minor: 





Five cents. 

7706 

75% copper, 25% 





nickel. 

l6 

62 

Three cents. 

3° 

75% copper, 25% 





nickel. 

14 ^ 

34 

Two cents. 

96 

95% copper, 5% 





tin and zinc. 

18 

60 

One cent. 

48 

95% copper, 5% 





tin and zinc. 

15 

43 


4 










































26 


The table below gives the organization of the mint at Philadel¬ 
phia. 


GENERAL OFFICERS. 

i .Superintendent. 

1 Assayer. 

1 Melter and refiner. 

1 Coiner. 

1 Engraver. 

1 Cashier. 

1 Chief Clerk. 

1 Assistant assayer. 

1 Ass’t melter and refiner. 

1 Bookkeeper. 

1 Weigh clerk. 

1 Abstract clerk. 

1 Cashier’s clerk. 

1 Warrant clerk. 

1 Register of deposits. 

1 Assistant weigh clerk. 

1 Assayer’s computing 
clerk. 

1 Medal clerk. 

1 Assistant bookkeeper. 

1 Register of warrants. 

ASSISTANTS, WORKMEN AND ADJUSTERS. 

General Department. 

1 Doorkeeper. 

1 Messenger. 

1 Painter. 

1 Gas fitter. 

1 Gatekeeper. 

1 Helper. 

6 Assistants. 

5 Conductors. 

6 Cabinet employes. 

16 Night watchmen. 

6 Carpenters. 

2 Engineers. 

1 Fireman. 

1 Oiler. 

8 Machinists. 

2 Adjusters of scales. 

3 Blacksmiths. 

28 Laborers. 

12 Female helpers. 

Assayer's Department. 

1 Assistant assayer. 

1 Weigher. 

1 Assistant. 

1 Foreman. 

1 Helper. 

2 Workmen. 

Melter and Refiner 1 s Depart¬ 
ment. 

1 Office clerk. 

1 Foreman. 

12 Melters. 

4 Deposit melters. 

1 Refiner. 

2 Sweep cellar operatives. 

1 Furnace builder. 

1 Hoister. 

1 Gatekeeper. 

1 Laborer. 

19 Helpers. 

Coiner's Department. 

1 Chief weigher. 

1 Assistant weigher. 

1 Hoister. 

1 General foreman. 

7 Counters (3 ladies). 

29 Coining room em¬ 
ployees (21 ladies). 
10 Annealers. 

9 Cleaners. 

12 Rollers. 

16 Cutters. 

3 Medal room employes. 
83 Adjusters. 

51 Temporary adjusters. 

Engraver's Department. 

2 Engravers. 

5 Die makers. 

1 Assistant. 


I he chimneys are cleaned once every year, during the last week 
in June, previous to making up the final settlement. The front of 
the flue to the ceiling is first taken down and carefully scraped. 
Most of the flue dust containing gold is to be found here. The 
surfaces of these bricks are very carefully scraped. The doors and 
windows all being closed, a steel brush is run up and down the rest 
of the flue from the roof, the top of the flue being covered while 
this operation is being performed. All the material so collected is 
put through the Kent’s amalgamator. 

The following table gives the wastage and losses on sales of 
these sweeps for 1885.* These losses are paid from surplus bul- 

* Report of the Director of the United States Mint for 1885. 






















2; 


lion, as tar as practicable, and the balance reimbursed from the 
appropriations and silver profit fund : 


LOSSES. 


Melter and refiner’s gold wastage, 

Coiner’s gold wastage, ..... 
Melter and refiner’s silver wastage, 

Coiner’s silver wastage, .... 

Loss on sale of sweeps, .... 

. $146 70 

50 81 
. 1561 81 

. 3089 26 

• 4593 04 

Total,. 

. $9441 62 

EXPENDITURES. 


From contingent appropriation, n . 

P'rom parting and refining appropriation, 

From surplus bullion, ..... 
From silver profit fund, .... 

. $483 69 

. . . 457 24 

1491 24 
. 7009 45 

Total,. 

. . . $9441 62 


The following are the charges imposed at the Coinage Mints and 
Assay Office at New York on deposits and purchases of bullion. 

Deposit melting charge* on all bullion, or coin not required to 
be parted or refined : 

P'or each melt of 1000 ounces or less, . . . ioo cents. 

Over 1000 ounces,.of I cent P er oz - 


Parting and refining charges. I .—Parting Gold and Silver , or Refining Gold. 

(Rate per ounce, gross.) 


On bullion containing 

At Phila¬ 
delphia. 

At New 
Orleans. 

At 

New York. 

At San 
Francisco. 

At 

Carson. 

Under 200 M, gold. 

From 200 M to 399^4 M, gold. 

P'rom 400 M to 699^ M, gold. 

P'rom 700 M and over, gold. 

Over 100 M, base metal additional 

1 J cents. 

2 “ 

D 

4 “ 

i cent. 

IJ cents. 

2 “ 

3 “ 

4 “ 

1 cent. 

1 cent. 

2 cents. 

• 3 “ 

4 “ 

1 cent. 

2 cents. 

3 “ 

4 “ 

6 “ 

b cent. 

2 cents. 

3 “ 

4 “ 

6 “ 

i cent. 


In addition to the above charges, on deposits requiring parting, 
or refining, for each deposit of 1000 ounces or less, a charge of ioo 
cents ; over 1000 ounces, j 1 ^ of I cent per ounce, gross is made. 
For gold coin or standard gold bars, the rate per ounce charged 


* Report of the Director of the United States Mint for 1S85, p. 133. 



























28 


is imposed only on the number of ounces required to be refined 
to raise the whole to standard. 

Silver allowed the depositor is calculated on the basis of refining 
the gold to 990 M. 

IT .—Refining Silver. 

(Rate per ounce,gross.) 


On bullion containing 

At Phila- 

At New 

At 

At San 

At 

delphia. 

Orleans. 

New York 

Francisco. 

Carson. 

Less than 897 M, silver. , 

i cents. 

i J cents. 

I ^ cents. 

2 cents. 

2 cents. 

From 897 M to 979^ M, silver... 

i cent. 

I cent. 

1 cent. 

T 1 “ 

1 

T 1 << 

I 2 

From 980 M to 997^ M, silver... 

1 u 

1 « 

2 

1 it 

1 cent. 

I cent. 


In addition to the above, on silver deposits requiring refining, 
a charge on each deposit of 1000 ounces or less, 100 cents; over 
1000 ounces, j 1 ^ of 1 cent per ounce, gross is made. For standard 
or sterling bars the rate per ounce is charged only on the number 
of ounces required to be refined to raise the whole to the fineness 
of such bars. 

TOUGHENING CHARGE. 

Gold bullion, . . . . . y to 2 cents per ounce, gross. 

Silver bullion, . . . . . % to 1 cent per ounce, gross. 

ALLOY CHARGE. 

On the number of ounces of copper re¬ 
quired to reduce the bullion to stan¬ 
dard, ...... 2 cents per ounce, troy. 


BAR CHARGE. 

On bullion deposited for fine bars not required to be parted or 
refined, and for standard, sterling, or unparted bars : 


Bars of 

At Phila¬ 
delphia. 

At New 
Orleans. 

At 

New York. 

At San 
Francisco. 

, At 
Carson. 

Fine gold, per $100 value. 

Fine silver, per ounce, fine. 

Standard gold, per $100 value. 

Standard silver, per ounce, standard 
Sterling silver, per ounce, gross.... 
Unparted bullion, per ounce, gross 

5 cents, 
f cent. 

10 cents. 
\ cent. 

i “ 

1 a 

2 

5 cents. 

I cent. 

10 cents. 
k cent. 

1 “ 

1 << 

2 

4 cents. 

j 'q cent. 

10 cents. 
h cent. 

1 “ 
l “ 

10 cents. 
$ cent. 

10 cents. 
J cent. 

1 Ci 

1 it 

5 

10 cents. 
I cent. 

10 cents. 

i cent. 

1 u 

2 

4 “ 
































2 9 


Charges imposed at the Assay Offices, other than New York, on 
deposits of bullion, at the Mint at Denver conducted as an Assay 
Office, and the Assay Offices at Charlotte, N. C.; Boise, Idaho; 
Helena, Mont.; and St. Louis,, Mo. 

The operations of these institutions are confined by law to the 
receipt, melting, assaying, and stamping of bullion, and returning to 
depositors the identical bullion in unparted bars, or, in the case of 
gold bullion, the value in coin or unparted bars, as may be preferred 
by the depositor. 

1. For melting, refining by fluxes, assaying and stamping of 
bullion, of i per cent, on the gross value of the bullion. 

2. When more than one melt is necessary, or extra materials 
are required to remove the base metals contained in deposits to 
render the resulting bullion ductile, an extra charge corresponding 
therewith must be made. 

3. Upon gold bullion deposited for payment of its value from 
the bullion fund, in addition to the assay office charge, the same 
charges as those imposed by the mint to which such bullion is 
required to be forwarded, and a further charge to cover the cost 
of transportation, will be collected of the depositor. 

The following table gives the earnings and expenditures of the 
mint for the year 1884-85.* 


EARNINGS. 


Parting and refining charges, ..... 

$12,188 

02 

Melting, alloy, and bar charges, .... 

6 33 

3 6 

Charge for assaying, melting, and stamping, . 

. .... 


Seignorage on standard silver dollars coined, 

• 2,250,873 

35 

Seignorage on subsidiary silver coined, . 

' 10,197 

61 

Seignorage on minor coins manufactured, 

452,351 

40 

Profits on sale of medals and proof coins, 

2,566 

59 

Receipts from assays of ores and bullion, 

392 

00 

Deposit melting-room fluxes and sweeps, 

b 2 57 

73 

Surplus bullion returned by melter and refiners, 

• • • • 

• 

Gain on bullion shipped the mint for coinage, 

• • • • 

• 

Proceeds of sale of old material, .... 

712 

3 r 

Profits from redemption fund, .... 

12 

99 

Total,........ 

. $2,731,185 

36 


* Report of the Director of the United States Mint for 1885. 









30 


EXPENDITURES AND LOSSES. 




Salaries of officers and clerks, .... 

. 

$40,673 

9 1 

Wages of workmen and adjusters, .... 

• 

367*854 

5 1 

Contingent expenses, less amount paid for wastage 

and 



loss on sweeps sold, ...... 

• 

127,259 

82 

Parting and refining expenses, less amount paid 

for 



wastage and loss on sweeps sold, 

• 

7*793 

73 

Wastages of the operative departments, . 

• 

4,848 

58 

Loss on sweeps of the year, ..... 

• 

4*593 

04 

Expenses of distributing silver coins, 

• 

28,922 

34 

Expenses of distributing minor coins, 

• 

12,251 

98 

Minor coinage metal wasted, ..... 

• 

405 

29 

Loss on sale of plumbic melts, .... 

• 

• . . 

• 

Total, •••••••• 

# 

$ 594,603 

20 


In conclusion I wish to express my thanks to the officers of the 
mint who have given me every facility for studying this very in¬ 
teresting process. 








• • 






















• • 

•• •. . 
























































* 


































































■ 

































































































































' 





















